Question 9: The most common iterative method of square root calculation by hand is known as the "________" or "Heron's method" after the first century Greek philosopher Heron of Alexandria who first described it.

Question 10: This is done by introducing a new number, denoted by i (sometimes j, especially in the context of electricity where "i" traditionally represents electric current) and called the ________, which is defined such that i2 = −1.